Electric lamp



.Jan. 11, 1938' H. E METCALF 2,105,430

ELECTRIC LAMP Original Fil ed Sept. 18, 1929 2 Sheets-Sheet l IE'lE lII. .II

ll 24 ll ATTO Jan. 11, 1938. H. E. METCALF ELECTRIC LAMP Original Fi ledSept. 18, 1929 2 Sheets-Sheet 2 INVENTOR.

Patented Jan. 11,1938

UNITED STATES PATENT OFFICE ELECTRIC LAMP York Application September 1:,1929, Serial No. 393,4:1

. Renewed June 25, 1936 'lOla-ims.

This, invention relates generally to the construction of electric lampsutilized for illuminating purposes, and which employ light sources suchas metallic filaments heated to mean-- 5 descence by means of anelectric current. The

invention is of particular value where it is desired to produce a sourceof illumination of high candle power, as for example in the taking ofmotion pictures,'or for motion picture proiection work. It will beobvious that the invention is applicable to electric lamps in generalwhich have light sources of high heat intensity.

Inthepast,ithasbeencommontoutilize' metallic filament electric lamps ofrelatively high wattage consumption for the production of a light sourceof relatively high candle power. By lamps of high wattage consumption, Ihave particular reference to lamps consuming one kilo-- watt or more ofelectrical energy. Because of an dimensions of the filaments and therelatively high temperatures at which they are operated,

it has been necessary in such lamps to utilize relatively largeevacuatedenvelopes. Even with such construction, while mechanical failure of asthe evacuated envelopes may be avoided, the walls of the lamp are heatedto a relatively high temperature and dissipatethls heat to convectioncurrents of air and by radiation. imparting heat to convection currentsof air surrounding a the lamp is frequently a serious objection, as forexample when employing the lamp in a motion I picture projection room orin a soundproof motion picture recording studio. Furthermore, the lightspectrum from such lamps contains a relatively high percentage of heatrays, which are frequently objectionable. Thus when using'such a lamp ina motion picture projection machine, a fire haurd iscreated in that thenature of the light is apt to heat inflammable film to cause acombustion, Furthermore, it is commonly appreciated that lamps of thischaracter have a relatively short and uncertain life, largely because ofthe high temperature to which the parts of the lamp are heated.

as It is an object of the present invention to devise an electric lamphaving a light source which can produce a high deg'reeof illumination,

without imparting an objectionable amount of heat to the air of the roomor enclosure in which so the lampi s being operated.

It is a further object of this-invention to devise a lamp which willproduce substantially cold light, that is, a light having a relativelylow percentage of heat rays.

5 {It is a further obiectof invention to devise a lamp of the abovecharacter which will be relatively compact, and which will have arelatively long life.

Further objects of the invention will appear from the followingdescription in which the pre- 5 ferred embodiments of the invention havebeen set. forth'in detail. It is to be understood that the appendedclaims are to be accorded a range of equivalentsconsistent with thestate of the prior 10 art.

Referring to the drawings:

Figure 1 is a side elevational view, partly-in cross section,illustrating an electric lamp incorporating the invention.

Fig. 2 is a cross sectional view, taken along the line 2-2 of Fig.1.

Fig. 8 is a circuit diagram illustrating the manner in which-I prefer tointerrelate the circuit for energizing my lamp, with the source ofcooling fluid.

Pig. 4 is a side elevational view,'partly in cross section, illustratinga modified form of electric lamp incorporating my invention.

Fig. 5 is a cross sectional view taken along the line l-lof Fig. 4. 1

Fig. 6 is a side elevational view partly in cross section, illustratinga further modified form of my invention.

Referring first to l igsai and 2 for a detailed description of onespecific embodiment of my insovention, I have shown a metallic filamentll -made of some suitable metal. such as tungsten,

positioned within an envelope I! of light transmitting material, such asglass. 'Hiis envelope is evacuated or contains an inert gas so as toserve to protect the-filament from deterioration. For operablysupporting the filament, there are shown members II and ll of insulatingmaterial, which are connected by the metallic spacing rods ll.'lhelowerendsofrodsiiareshowng projecting through insulating member Iand are welded or otherwise suitably connected to metallic members ll.Envelope i2 is shown formed with the usual reentrant tube ll, having'apressliatitsinnerend. Rodsorbarsliare 4,5 ll

connected to members l1, and are suitably sealed in press is. Filamentll has been shown in the form of a coiled wire having its terminalsconnected to metallic rods i8, and looped a plurality of timesbetweensupport members II and M. The ends of the looped portions can beconnected to members it and it by members 22. The lower end of envelopei2 is shown mounted 1 upon a conventional base 24, provided with contactprongs Ilfand which is. adapted to 00- operate with a. conventional lampsocket. Suitable electrical conductors connect prongs 26 with rods 2|.While the filament may take various forms, I prefer for projection work,that it be disposed substantially in a common plane as shown in Fig. 2.

Surrounding the envelope I2, I provide another outer envelope 21 whichis preferably spaced from the inner envelope I2, at least for thatportion of the inner envelope which immediately surrounds filament II.Envelope 21 is also made of some light transmitting material such asglass. The lower end of envelope 21 is sealed with respect to the innerenvelope I2, as indicated at 28. The spacing between envelopes I2 and 21forms a fluid chamber 29.

Chamber 29 is for the purpose of surrounding or encompassing the innerenvelope I2 with a suitable cooling fluid preferably a liquid such aswater. This cooling liquid is circulated through the chamber 29,preferably in such a manner that currents are formed to cause the liquidto swirl about the envelope I2. For this purpose, there is shown a tube3| connected to the lower portion of outer envelope 21, and arranged todischarge liquid into chamber 29 in a tangential direction as shown inFig. 2. Liquid is removed from the upper portion of chamber 29, as bymeans of the tube 32. It is apparent that because of the tangentialrelationship of inflow tube 3|, liquid introduced into chamber 29 willswirl about envelope I2 as it advances upwardly within chamber 29, andwill finally be discharged through outflow tube 32. The imparting of aswirling movement to the cooling liquid insures adequate and uniformcooling of the envelope I2. Removal of liquid from the upper part ofchamber 29 prevents the collecting of gas or air within the chamber.This gas is dissolved in the cooling fluid and is released in the formof bubbles on i the outer surface of the inner envelope I2 by the heatof the filament. The rapid swirling of the liquid sweeps away thebubbles before they become large enough to obstruct light, and wouldcause a gas or air pocket at the top of the chamber if not immediatelyremoved by the outflow tube.

In operating the lamp described above, the filament is connected to asuitable source of electrical energy, and inflow pipe 3| is connected toa source of liquid under pressure, such as a water supply pipe. Assuminga. relatively high wattage consumption for the filament, say from 1 to25 kilowatts or more, a large amount of heat will be imparted to thewalls of the inner envelope I2, but this envelope will be kept at arelatively low temperature, since the heat is immediately con ducted tothe liquid within the chamber 29. Likewise, the outer envelope 21 willbe kept at a relatively low temperature, substantially the same as thetemperature of water flowing through chamber 29, so that it will notheat air within the room or enclosure in which the lamp is operating.The water within chamber 29 also serves as a light filter medium toabsorb a substantial amount of heat rays from the light radiated fromthe filament II. Thus, the light generated by the lamp is relativelycold, as is evidenced by the fact that when my lamp is utilized in amotion picture projection machine, an inflammable motion picture filmmay be stopped for an indefinite period without causing the film to .beignited.

In Fig. 3, I have represented a special electrical circuit arrangementwhich will preclude injury to the lamp in the event of failure of thesupply of cooling liquid. In this view, the lamp of my invention hasbeen indicated generally as 34, and has its contacts 26 connected to thecurrent supply lines I and 2. Connected in series with contacts 26,Iprovide a pair of cooperating contacts 36 and 31. Contact 31 is carriedby a flexible diaphragm 36, which in turn forms one wall of a liquidpressure chamber 39. Pipe 4| is connected to a source of liquid underpressure, such as a water supply pipe, and is in communication withchamber 39 thru a restricted nozzle or orifice 42. The object of orifice42 is to discharge the liquid against diaphragm 36 with considerablekinetic energy thus causing this diaphragm to normally retain contacts36 and 31 closed. Discharge pipe 43 is connected with chamber 39, and inturn is connected to tube 3| of lamp 34, through a hose or pipeconnection 44. When the lamp is in normal operation, continualintroduction of liquid through pipe 4| retains contacts 36 and 31closed. However, in the event of the failure of the source of liquidsupply, diaphragm 38 moves sufficiently to open contacts 36 and 31, thusdisrupting the supply of current to the lamp filament.

A modified form of my invention is shown in Figs. 4 and 5, in which theinflow and outflow tubes to the outer envelope project through a portionof the lamp base. Thus, in this instance, the lamp base I24 includes anannular collar 46, within which the lower end of envelope I21 extends.Suitable moldable material or cement 41, serves to secure and sealenvelope I21 with respect to the base, and also with respect to thelower portion of the inner envelope II2. Envelope II 2 is likewise shownsecured to and sealed with respect to the base, by means of moldablematerial or cement 48. Inflow pipe I3I, which in this instance ispreferably made of metal, extends through a portion of the base, as forexample thru the collar 46. The inner end portion of this tube I3I, ispreferably directed in a tangential direction, as shown in Fig. 5.

The outflow pipe I32 is likewise preferably made of metal, and is alsoshown extended through the collar 46. The inner end portion 52 of tubeI32 is shown extending upwardly between envelopes H2 and I21, andcommunicates with the upper portion of chamber I29, as shown in Fig. 4.Tube 52 is preferably flattened as shown in Fig. 5, in order to preventobjectionable restriction of the chamber I29.

A further modified form of my lamp is shown in Fig. 6 which is ofparticular value for substitution in place of the carbon electrodes ofan arc lamp. In this instance, the terminals of the filaments are takenout through reentrance tubes 2I8, located at both ends of the innerenvelope 2|2. Suitable bases 224 are mounted on the ends of envelope2|2, and carry the contact members 56. These contact members are formedso that they can be operably engaged by the clamps normally used forholding arc electrodes. The outer envelope 221 in this instance has eachend sealed with respect to collars 246, in the manner explained withrespect to Figs. 4 and 5, and these collars are in turn formed as a partof the base structures 224. Liquid inflow tube 23| extends laterallythrough collars 246 and has a tangentially directed portion 25I, asshown in Fig. 4. Outflow tube 232 is at the upper end of the lamp, andextends laterally through the corresponding collar 246. The innerendportion 252 01 pipe 232, communicates with the upper portion ofchamber229. The operation of the lamp shown in Fig. 6 as well as thelamp shown in Figs. 4 and 5, is substantially the same as the lampdescribed with respect to Figs. 1 and 2.

By utilizing the principles of my invention, it is possible tomanufacture a commercial lamp for current consumption as high askilowatts or more. Such lamps are comparatively compact, they give acold light, and dissipate practically no heat to the surrounding air.For example, one lamp which I have constructed utilizes about threekilowatts, and is only approximately 3 inches in diameter. When used ina confined room or space, they cause practically no increase in thetemperature of the surrounding air.

1. A liquid cooled lamp comprising a light source, a pair of concentriccylindrical transparent envelopes disposed around said source and spacedto form a chamber therebetween, an inlet conduit opening tangentiallyinto one end of said chamber, and a transparent outlet conduit enteringthe same end of said chamber and extending through said chamber to openat the other end thereof.

2. A liquid cooled lamp comprising a light source, a pairof concentriccylindrical transparent envelopes disposed around said source and spacedto form a chamber therebetween, an inlet conduit opening tangentiallyinto one end of said chamber, and a transparent outlet conduit enteringthe same end of, said chamber and extending through said chamber to openat the other end thereof, said outlet conduit being flattened withinsaid chamber to reduce obstruction to rotational flow of liquid therein.

3. In combination, a cylindrical inner envelope, a light source mountedon one end thereof with energizing leads sealed therethrough, acupshaped base having a rim adapted to receive the end of said envelope,said base also having a laterbase to seal said chamber, and inlet andoutlet conduits entering said chamber through said base and said cement.

4. In combination, a vertically disposed, sealed, cylindrical innerenvelope having a light source mounted therein, a cylindrical outerenvelope disposed about said inner envelope in axial alinement therewithand sealed to said inner envelope to provide an annular chamber aboutthe major portion of the surface of said inner envel pe. an

inlet conduit entering said chamber at one end thereof in axialparallelism with said envelopes and provided within said chamber with anarcuately directed portion lying transverseto the axis of saidenvelopes, and an outlet conduit entering said chamber adjacent saidinlet conduit and parallel with a portion thereof, said outlet conduitextending longitudinally of said chamber and terminating at a pointadjacent the axis of said envelopes.

5. In combination, a sealed cylindrical envelope having a light sourcemounted therein and energizing leads for said light source sealedthrough opposite ends thereof, a cup-shaped base having a flange thereonfor engaging said envelope, disposed at each end of said envelope, n.cylindrical memberdisposed about said envelope, an annular flange oneach of said bases for engaging an end of said cylindrical member, aquantity of cement in-each base for sealing said flanges to saidenvelope and said cylindrical member to provide a fluid-tight annularchamber about said envelope, a fluid conduit passing through each ofsaid bases and said cement thereof and opening into said chamber atopposite ends thereof, and a connection stud on each of said bases andconnected with said energizing leads, said studs be- .ing disposed inaxial alinement with each other.

wherein the outlet conduit is of flattened section within the chamber toreduce obstruction to rotational flow of liquid therein.

HERBERT E. mm.

